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August 29, 2002
A: FROM MENTOR JOAN LUSK. FOR BIO. CLICK
HERE.
This isn't exactly an answer to your question, but I can't
resist.
This summer I stopped over in Iceland for a couple of days,
and a
tour guide said she was often asked how many active volcanos
there
are in Iceland. Her answer was "one - the whole island
is a
volcano." The real answer for Iceland or our land would
depend on
how you define "active" - how long must a volcano
have failed to
erupt before we think it never will again? And how far apart
must
the activities be before we call them separate volcanos. The
whole
Hawaiian archipelago, as I understand it, is the result of
one hot
spot deep in the earth, erupting from time to time at different
points on the surface as the surface moves relative to the
core.
Midway Island - a long way from Hawaii - is the oldest of
these sites
to reach above sea level, and Kilauea is probably the newest
(though
don't I recall that a new site is developing just off shore
from
there? My memory could be faulty.) So we certainly think of
Midway
as non-active and separate from Kilauea - but at a deep level
they're
all resulting from a single, still-active spot.
this site - from a reliable source - says that there is no
definitive
definition of when a volcano is considered active, dormant
or extinct:
http://volcanoes.usgs.gov/Products/Pglossary/volcano.html
and this one lists the 101 top FAQ's posed to volcanologists
at the U
of North Dakota:
http://volcano.und.edu/vwdocs/frequent_questions/top_101/Top_101.html
In response to a question about when a volcano counts as "active",
the authors point out that there have been a number of eruptions
from
"extinct" volcanos. So our ability to predict eruptions
could stand
some improvement... there's still work to be done by the next
generation of volcanologists!
And one more thing: the movies of Kilauea on the site I mentioned
before didn't "move" for me, but these do
http://volcano.und.edu/vwdocs/movies/Steves_Stuff/Kilauea_erz.html
Enjoy!
August 29, 2002
A: FROM MENTOR KRISTIN TAGHON. FOR BIO
CLICK HERE.
Kelly,
I did a search and it was very hard to come up with an exact
number, or even an
estimate. I found this site which has a record of current
eruptions. You can
count the ones in U.S. but this does not tell us which are
active, just where
there has been the most recent activity.
http://volcano.und.edu/vwdocs/current_volcs/current.html
This site has all the volcanoes in Alaska and you can read
about each one. I
counted 56 volcanoes, but I don't think all of them are active.
I read in one article that Alaska has more than 40 active
volcanos, 80% of the
active volcanoes in the U.S. This would tell me that, in the
U.S., there are
between 50 and 60 active volcanoes in the U.S. Perhaps someone
can find more
accurate information.
Kristin
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